This invention relates generally to the field of sanding and abrading tools formed by assembling a group of sanding discs together in aligned stacked arrangement to be held together by a centrally disposed mandrel, such tools being commonly referred to in the art as "star heads". These devices are used by engaging the mandrel with a power tool and, when rotating, are applied peripherally to the surface to the sanded so that all of the discs wear at substantially the same speed.
In prior art constructions, it is usual to provide a plurality of rectilinear strips of abrasive coated sheet material, the strips being skip cut and having a centrally disposed opening. The strips are assembled on a mandrel in such manner as to provide a substantially continuous peripheral surface, although the ends of only a few of the strips are in contact with the work surface at any given instant.
U.S. Pat. No. 5,125,192 granted Jun. 30, 1992 to Welsch, discloses an improvement in this type of device characterized in the substitution of the above-mentioned strips by a sheet of abrasive material which is die cut to provide a plurality of radially extending projections joined at a centrally disposed hub supported by the mandrel. This construction has the advantage of placing considerably more abrasive in a common plane to contact the work surface, and as might be expected, the efficiency of sanding is substantially increased. However, because of the triangularly shaped open spaces between the projections, substantial gaps in the amount of abrasive material available occur when the device is in use, and the arcuately shaped end edges of the parallel fingers formed in the projections are disposed such that a major portion of each edge is substantially parallel to the direction of rotational movement, thereby limiting the abrasive effect of each finger.